1. Field of the Invention
The invention relates to automated quality control aids in a silicon integrated circuit manufacturing environment and, more particularly, to a method and apparatus for determining thickness of a metal deposited on a silicon wafer during such a manufacturing process and for storing and manipulating the determined thickness data.
2. Background of Invention
In the manufacture of silicon integrated circuit devices, a common procedure is deposition of a metal on a silicon wafer. Thicknesses of deposited metal and silicon wafer are important because the thicknesses affect conductive and resistive properties of a final silicon integrated circuit device obtained from the manufacturing process. It is common then to employ in the manufacturing process some means to measure the wafer and metal thicknesses.
A device referred to as an "M-Gage" has previously been used in silicon integrated circuit manufacturing processes to measure silicon wafer and deposited metal thicknesses. The M-Gage measures the metal and silicon thicknesses by detecting a resistivity of the wafer with the deposited metal. That resistivity is then converted by a formula, based on known properties of the silicon and metal, to a thickness measurement.
In the past, a calculator, such as a Hewlett-Packard 97S or 9815S calculator, has been employed with the M-Gage. The calculator is attached to the M-Gage via a 50-pin binary-coded decimal ("BCD") interface socket located on the rear of the M-Gage. In this arrangement, the calculator receives resistivity data from the M-Gage and, based on formulas and variables programmed into the calculator, the calculator gives thickness data.
This prior arrangement of M-Gage and calculator has proven effective in most instances. This arrangement, however, has certain disadvantages. For example, the calculator may store only limited amounts of data. For many manufacturing processes, greater data storage capacity is desired. In addition, this arrangement of M-Gage and calculator requires substantially continual monitoring and attention by quality control personnel. That monitoring and attention requires not only hand operation of the M-Gage and calculator, but also saving and manipulation of data obtained from the M-Gage and calculator is performed by hand.
As those skilled in the art will appreciate, greater automation of the measurements and thickness determinations would lead to greater efficiency and quality in the silicon integrated circuit manufacturing process. It would be advantageous too, if automation provided for greater data storage capacity and better manipulation, categorization, and compilation of the data obtained during the silicon integrated circuit manufacturing process.
The present invention provides those and other improvements and advantages in the technology. Those skilled in the art will understand and appreciate these advantages and the applications of the invention.